Reel spool shaft for use with cores

ABSTRACT

The invention employs a fluid cushion between a shaft and cylindrical core to reduce friction between the core and shaft. Reduced friction at the shaft/core interface lowers the forces required to separate rolls of web material from the shaft. Lower separation forces should mean less damage to the wound web material and less wear and tear on the shaft and extraction equipment.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 60/535,875, filed Jan. 12, 2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to the production of rolls of web material wound on cores supported by a shaft of the machine producing the material and more specifically to removal of rolls of web material from the shaft.

2. Description of the Related Art

Significant losses in product can occur during the operation of extracting a shaft (reel spool) from cylindrical cores placed thereon to be wound with web materials. The losses occur because the friction forces between the inside diameter of the reel spool core and the outside of the shaft are sometimes high and therefore, significant force may be required to extract the shaft from the core. High shaft extraction forces can damage the wound web material, shaft, core and/or extraction equipment. The friction forces between the spool and core may be aggravated by the weight of the material being wound on the core and/or compression of the core in the radial direction due to the compressive forces caused by winding a web of material around the core.

Many products, such as paper, tissue, textiles, plastics, films or polymer webs are wound on cylindrical cores in the machine producing the product. In this application, the word “web” will be used to refer to these materials and is intended to encompass all materials of a width greater than 10 inches (254 mm) that are wound onto any type of cylindrical cores, shafts or the like. Typically, the cores are cylindrical paper, cardboard or plastic tubes supported for rotation on shafts (also referred to as spools or reel spools) in the production equipment. The shaft and its fully wound roll or rolls of web material must be periodically removed from the production equipment and replaced with another shaft equipped with empty cores. The removed shaft is then separated from the rolls of web material, provided with empty cores and re-used.

Past methods of separating the shaft from the rolls of web material have involved using a shaft-extracting device or a roll-extracting device. Shaft extracting devices typically support the roll of web material on a floor, table, or like surface, then attach an external device to the shaft and pull the shaft out of the roll core. Shaft extractors may be fixed, or adjustable in elevation.

Roll-extracting devices separate the rolls from the shafts by fixing the shafts in a support device, which is usually cantilevered. The elevation of the shaft (and hence the rolls of web material) is changed to rest the outside surface of the wound web material on a cart, or the like. The cart is then moved in the opposite direction, away from the fixed support of the shaft, and pulls the rolls of web material axially off the shaft.

Excessive shaft extraction forces may damage the cores, shaft, shaft extracting equipment and the wound web material.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a new and improved apparatus and method for reducing the friction between the core of a roll of web material and a shaft supporting the roll of web material.

An aspect of the invention relates to producing a fluid cushion, preferably of compressed air, between the shaft and core (with the alternative introduction, application or activation of any solid, liquid or gas or other means as described below), to reduce friction between the core and shaft. Reduced friction at the shaft/core interface lowers the forces required to separate rolls of web material from the shaft. Lower separation forces should mean less damage to the wound web material and less wear and tear on the shaft and extraction equipment.

According to further aspects of the present invention, the cushion/bearing material (encompassed by the term ‘fluid’, for the remainder of the specification) may be introduced to the core/shaft interface anywhere through the shaft structure. Alternatively, the fluid may be introduced directly between the reel spool and core, without first passing through the shaft itself.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view through a reel spool shaft and two rolls of web material, where the shaft is modified according to aspects of the present invention;

FIG. 2 is a side view, partially in phantom, of an alternative reel spool shaft according to aspects of the present invention;

FIG. 3 is an enlarged sectional view of the reel spool shaft of FIG. 2, taken along line 3-3 thereof;

FIG. 4 is a side view, partially in phantom, of a further alternative reel spool shaft according to aspects of the present invention; and

FIG. 5 is an enlarged sectional view of the reel spool shaft of FIG. 4, taken along line 5-5 thereof.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The web material, whether paper, tissue, textile, plastic, film or polymer web, is wound on cylindrical cores of paperboard, cardboard or plastic supported for rotation by shafts in or near the equipment producing the web material. The word ‘web’ is used herein to refer to all materials of a width greater than 10 inches (254 mm) that are wound onto any type of cylindrical cores, shafts, or the like. When taking up the web material, it is important for the core to rotate with the shaft and not independently of the shaft. This typically means that the cores are configured to fit snugly over the shaft. This snug relationship between the core and shaft may be aggravated by atmospheric conditions such as humidity, variation in the size of the cores, the weight of the wound web material and by compressive forces exerted on the core by the wound web material. In combination, these factors frequently result in frictional forces between the core of a roll of web material and the supporting shaft that can be difficult to overcome. Forces generated during attempts to remove frictionally engaged cores from their shafts are frequently of such a magnitude as to damage the wound web material, the core, the shaft and/or the shaft extraction equipment.

The basic features of an exemplary embodiment are illustrated in FIG. 1. Rolls of web material 30 wound on cores 32 are supported on a reel spool or shaft 20. The illustrated shaft 20 is hollow, although the shaft may be solid or partially hollow along its length. A shaft is modified with a connection for introducing a fluid, preferably air or some other gas to the core/shaft interface. The connection may be in any form or location where the fluid will penetrate a significant portion of the area 36 between the shaft and core. The connection may be located on an end of the shaft, as in 38 a or 38 b. Alternatively, the connection may be positioned to inject air directly at the shaft/core interface 36 without passing through the shaft. In the context of this application, the term “aligned”, when referring to the relationship of the connection for introducing fluid, includes locations coaxial with the shaft axis of rotation and locations that are not coaxial with the shaft axis of rotation, but are substantially parallel thereto.

The injection of a pressurized fluid at the interface 36 of the core 32 and the shaft 20 produces a cushion or “fluid bearing” 40 between the core and the shaft. The fluid bearing 40 alters the coefficient of friction between the core 32 and the shaft 20, reducing the force necessary to produce relative motion between the core an the shaft.

The connection for introducing fluid is provided with a source of pressurized fluid. While compressed air is the most cost-effective fluid for the purposes of the present invention, other compressed gasses or liquids are compatible with the invention. A variation of the invention uses a lubricant introduced between the outside of the shaft and the core to reduce the friction between the core and shaft. The lubricant may be a fluid substance (air, as in the base invention, or liquids), or dry lubricants, including but not limited to graphite. In some cases, a carrier fluid, such as compressed air may be used to disperse a liquid or dry lubricant at the shaft/core interface.

An alternative embodiment of the inventive reel spool shaft 20 a is illustrated in FIGS. 2 and 3. Shaft 20 a is equipped with rolling elements 42 arranged to protrude through the shaft outside surface 44 to lower the forces required to remove the rolls of web material from the shaft. The rolling elements may be in a fixed location on the shaft relative to the center of spool rotation. Alternatively, the rolling elements may be movable as shown in FIG. 3, from a retracted position below the shaft outside surface 44 to an extended position where the rolling elements protrude from the shaft outside surface. The force to move the rolling elements 42 between the retracted and extended positions may be provided by pressurized fluid provided to the shaft through connection 38 a. Alternatively, the rolling elements 42 may be actuated by spring or electrical or mechanical means. The shaft outside surface 44 may be coated with a friction reducing coating 46 such as teflon to reduce friction between the core and the shaft at locations of contact with the shaft outside surface.

Another alternative embodiment of the inventive reel spool shaft 20 b uses low friction elements and/or materials on the shaft outside surface 44 of the shaft. As shown in FIGS. 4 and 5, the low friction materials are in the form of elongated bars 48 arranged to radially reciprocate between a retracted position below the shaft outside surface 44 to an extended position where the elongated bars 28 protrude from the shaft outside surface. The force to move the elongated bars between the retracted and extended positions may be provided by pressurized fluid provided to the shaft through connection 38 a. Alternatively, the elongated bars 48 may be actuated by spring or electrical or mechanical means. The shaft outside surface 44 may be coated with a friction reducing coating 46 such as teflon to reduce friction between the core and the shaft at locations of contact with the shaft outside surface. The elongated bars may be continuous along substantially the entire length of the shaft outside surface 44 or may be discontinuous longitudinally overlapping bars.

The present invention is applicable for use in conjunction with any and all types of shaft-extraction and or wound roll removal devices. Exemplary embodiments of the present invention have been set forth for purposes of illustration. The foregoing description should not be deemed a limitation of the invention. Various modifications, adaptations and alternatives may occur to one skilled in the art without departing from the spirit and the scope of the present invention. 

1. A shaft for supporting a web wound on a tubular core surrounding the shaft with frictional forces between said core and said shaft, said shaft comprising: a connection for receiving pressurized fluid pressurized fluid; and a fluid path communicating with said connection to inject said pressurized fluid between said spool and said core, wherein said injected fluid reduces the frictional forces between said core and said spool.
 2. The shaft of claim 1, wherein said shaft is partially or wholly hollow and said fluid path comprises a fluid inlet directing said pressurized fluid into said hollow shaft and a plurality of outlets through said shaft allowing fluid flow out of said shaft between said shaft and said core.
 3. The shaft of claim 1, wherein said fluid is compressed air.
 4. The shaft of claim 1, wherein said fluid is a compressed gas and includes a liquid or solid lubricant dispersed by said compressed gas.
 5. The shaft of claim 1, wherein said fluid is a lubricant.
 6. The shaft of claim 1, wherein said shaft has an outside surface adjacent an inside surface of said core, said outside surface including friction reducing elements.
 7. The reel spool of claim 6, wherein said friction reducing elements include a friction reducing coating on said outside surface.
 8. A method for reducing friction between a shaft and a tubular core surrounding the shaft, said method comprising: providing a fluid path to an annular interface between said shaft and said core; injecting pressurized fluid into said interface.
 9. The method of claim 8, wherein said shaft is partially or wholly hollow and the step of providing a fluid path comprises: injecting a fluid through an inlet communicating with an interior of said hollow shaft; and directing said pressurized fluid between said shaft and said core through perforations in said shaft.
 10. The method of claim 8, wherein said step of injecting pressurized fluid comprises: injecting compressed air into said interface.
 11. The method of claim 8, wherein said step of injecting pressurized fluid comprises: injecting compressed gas carrying a lubricant into said interface.
 12. The method of claim 8, wherein said step of injecting pressurized fluid comprises: injecting a liquid into said interface.
 13. The method of claim 8, wherein said shaft has an outside surface and said method comprises: configuring said outside surface with friction reducing elements.
 14. The method of claim 13, wherein said step of configuring comprises: coating said outside surface with a friction reducing coating.
 15. A shaft for receiving a core for installation in a web take-up system in a paper making machine, said shaft comprising: a cavity defined within said shaft; a plurality of fluid flow passages communicating between said cavity and an outside surface of said shaft; and a connection for receiving pressurized fluid, said connection communicating with said cavity.
 16. The shaft of claim 15, wherein said shaft has an axis of rotation and said connection is aligned with said axis of rotation.
 17. The shaft of claim 15, wherein said shaft has an outside surface including friction reducing elements.
 18. The shaft of claim 17, wherein said friction reducing elements include a friction reducing coating on said outside surface.
 19. The shaft of claim 15, wherein said shaft has an axis of rotation and said connection is coaxial with said axis of rotation.
 20. A shaft for receiving a core for installation in a web take-up system in a paper making machine, said shaft comprising: a generally cylindrical outside surface; and a plurality of friction reducing elements arranged to reciprocate between a retracted position radially inward of said outside surface and an extended position radially projecting from said outside surface; and means for moving said plurality of friction reducing elements between said retracted and extended positions, wherein said friction reducing elements in the extended position reduce frictional forces between a received core and said outside surface.
 21. The shaft of claim 20, wherein said shaft comprises a connection for receiving pressurized fluid and said means for moving comprises said pressurized fluid.
 22. The shaft of claim 20, wherein said friction reducing elements include rollers arranged to protrude from said outside surface when said friction reducing elements are in the extended position. 